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<h3><a name="toc">目录</a></h3>
<ul>
<li class="level1"><a href="#declare-the-birthdayparty">声明BirthdayParty</a></li>
<li class="level2"><a href="#define-the-birthdayparty">定义BirthdayParty</a></li>
<li class="level1"><a href="#running-the-example">运行这个示例</a></li>
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<h1 class="title">扩展QML -对象和列表属性类型的例子</h1>
<span class="subtitle"></span>
<!-- $$$referenceexamples/properties-brief -->
<p>导出C++的属性。</p>
<!-- @@@referenceexamples/properties -->
<!-- $$$referenceexamples/properties-description -->
<div class="descr"> <a name="details"></a>
<p>这个例子的基础是:</p>
<ul>
<li><a href="qtqml-referenceexamples-adding-example.html">扩展QML -添加类型的例子</a></li>
</ul>
<p>对象和列表属性类型示例显示了如何在QML中添加对象和列表属性。本例添加一个BirthdayParty类型，该类型指定一个BirthdayParty，由一个celebrant（庆祝者）和一组guest（宾客）组成。People是使用前面示例中构建的People QML类型指定的。</p>
<pre class="qml">

  <span class="type">BirthdayParty</span> {
      <span class="name">host</span>: <span class="name">Person</span> {
          <span class="name">name</span>: <span class="string">&quot;Bob Jones&quot;</span>
          <span class="name">shoeSize</span>: <span class="number">12</span>
      }
      <span class="name">guests</span>: [
          <span class="type">Person</span> { <span class="name">name</span>: <span class="string">&quot;Leo Hodges&quot;</span> },
          <span class="type">Person</span> { <span class="name">name</span>: <span class="string">&quot;Jack Smith&quot;</span> },
          <span class="type">Person</span> { <span class="name">name</span>: <span class="string">&quot;Anne Brown&quot;</span> }
      ]
  }

</pre>
<a name="declare-the-birthdayparty"></a>
<h2 id="declare-the-birthdayparty">声明BirthdayParty</h2>
<p>BirthdayParty类声明如下:</p>
<pre class="cpp">

  <span class="keyword">class</span> BirthdayParty : <span class="keyword">public</span> <span class="type"><a href="../qtcore/qobject.html">QObject</a></span>
  {
      Q_OBJECT
      Q_PROPERTY(Person <span class="operator">*</span>host READ host WRITE setHost)
      Q_PROPERTY(<span class="type"><a href="qqmllistproperty.html">QQmlListProperty</a></span><span class="operator">&lt;</span>Person<span class="operator">&gt;</span> guests READ guests)
  <span class="keyword">public</span>:
      BirthdayParty(<span class="type"><a href="../qtcore/qobject.html">QObject</a></span> <span class="operator">*</span>parent <span class="operator">=</span> <span class="number">0</span>);

      Person <span class="operator">*</span>host() <span class="keyword">const</span>;
      <span class="type">void</span> setHost(Person <span class="operator">*</span>);

      <span class="type"><a href="qqmllistproperty.html">QQmlListProperty</a></span><span class="operator">&lt;</span>Person<span class="operator">&gt;</span> guests();
      <span class="type">void</span> appendGuest(Person<span class="operator">*</span>);
      <span class="type">int</span> guestCount() <span class="keyword">const</span>;
      Person <span class="operator">*</span>guest(<span class="type">int</span>) <span class="keyword">const</span>;
      <span class="type">void</span> clearGuests();

  <span class="keyword">private</span>:
      <span class="keyword">static</span> <span class="type">void</span> appendGuest(<span class="type"><a href="qqmllistproperty.html">QQmlListProperty</a></span><span class="operator">&lt;</span>Person<span class="operator">&gt;</span><span class="operator">*</span><span class="operator">,</span> Person<span class="operator">*</span>);
      <span class="keyword">static</span> <span class="type">int</span> guestCount(<span class="type"><a href="qqmllistproperty.html">QQmlListProperty</a></span><span class="operator">&lt;</span>Person<span class="operator">&gt;</span><span class="operator">*</span>);
      <span class="keyword">static</span> Person<span class="operator">*</span> guest(<span class="type"><a href="qqmllistproperty.html">QQmlListProperty</a></span><span class="operator">&lt;</span>Person<span class="operator">&gt;</span><span class="operator">*</span><span class="operator">,</span> <span class="type">int</span>);
      <span class="keyword">static</span> <span class="type">void</span> clearGuests(<span class="type"><a href="qqmllistproperty.html">QQmlListProperty</a></span><span class="operator">&lt;</span>Person<span class="operator">&gt;</span><span class="operator">*</span>);

      Person <span class="operator">*</span>m_host;
      <span class="type"><a href="../qtcore/qvector.html">QVector</a></span><span class="operator">&lt;</span>Person <span class="operator">*</span><span class="operator">&gt;</span> m_guests;
  };

</pre>
<p>该类包含一个成员来存储庆祝对象，以及一个<a href="../qtcore/qlist.html">QList</a>&lt;Person *&gt; 成员。</p>
<p>在QML中，列表属性的类型(guest属性是人员列表)都是<a href="qqmllistproperty.html">QQmlListProperty</a>&lt;T&gt;类型。 <a href="qqmllistproperty.html">QQmlListProperty</a> 是一个简单的值类型，包含一组函数指针。QML在需要读取、写入或与列表交互时调用这些函数指针。除了本例中使用的人员列表之类的具体列表外，使用<a href="qqmllistproperty.html">QQmlListProperty</a>还允许&quot;虚拟列表&quot;和其他高级场景。</p>
<a name="define-the-birthdayparty"></a>
<h3 >定义BirthdayParty</h3>
<p>BirthdayParty属性访问器的实现非常简单。</p>
<pre class="cpp">

  Person <span class="operator">*</span>BirthdayParty<span class="operator">::</span>host() <span class="keyword">const</span>
  {
      <span class="keyword">return</span> m_host;
  }

  <span class="type">void</span> BirthdayParty<span class="operator">::</span>setHost(Person <span class="operator">*</span>c)
  {
      m_host <span class="operator">=</span> c;
  }

  <span class="type"><a href="qqmllistproperty.html">QQmlListProperty</a></span><span class="operator">&lt;</span>Person<span class="operator">&gt;</span> BirthdayParty<span class="operator">::</span>guests()
  {
      <span class="keyword">return</span> <span class="type"><a href="qqmllistproperty.html">QQmlListProperty</a></span><span class="operator">&lt;</span>Person<span class="operator">&gt;</span>(<span class="keyword">this</span><span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span>
               <span class="operator">&amp;</span>BirthdayParty<span class="operator">::</span>appendGuest<span class="operator">,</span>
               <span class="operator">&amp;</span>BirthdayParty<span class="operator">::</span>guestCount<span class="operator">,</span>
               <span class="operator">&amp;</span>BirthdayParty<span class="operator">::</span>guest<span class="operator">,</span>
               <span class="operator">&amp;</span>BirthdayParty<span class="operator">::</span>clearGuests);
  }

  <span class="type">void</span> BirthdayParty<span class="operator">::</span>appendGuest(Person<span class="operator">*</span> p) {
      m_guests<span class="operator">.</span>append(p);
  }

  <span class="type">int</span> BirthdayParty<span class="operator">::</span>guestCount() <span class="keyword">const</span>
  {
      <span class="keyword">return</span> m_guests<span class="operator">.</span>count();
  }

  Person <span class="operator">*</span>BirthdayParty<span class="operator">::</span>guest(<span class="type">int</span> index) <span class="keyword">const</span>
  {
      <span class="keyword">return</span> m_guests<span class="operator">.</span>at(index);
  }

  <span class="type">void</span> BirthdayParty<span class="operator">::</span>clearGuests() {
      m_guests<span class="operator">.</span>clear();
  }

</pre>
<a name="running-the-example"></a>
<h2 id="running-the-example">运行这个示例</h2>
<p>示例中的main.cpp文件包含一个简单的shell应用程序，它加载并运行本页开头所示的QML片段。</p>
<p>文件：</p>
<ul>
<li><a href="qtqml-referenceexamples-properties-birthdayparty-cpp.html">referenceexamples/properties/birthdayparty.cpp</a></li>
<li><a href="qtqml-referenceexamples-properties-birthdayparty-h.html">referenceexamples/properties/birthdayparty.h</a></li>
<li><a href="qtqml-referenceexamples-properties-example-qml.html">referenceexamples/properties/example.qml</a></li>
<li><a href="qtqml-referenceexamples-properties-main-cpp.html">referenceexamples/properties/main.cpp</a></li>
<li><a href="qtqml-referenceexamples-properties-person-cpp.html">referenceexamples/properties/person.cpp</a></li>
<li><a href="qtqml-referenceexamples-properties-person-h.html">referenceexamples/properties/person.h</a></li>
<li><a href="qtqml-referenceexamples-properties-properties-pro.html">referenceexamples/properties/properties.pro</a></li>
<li><a href="qtqml-referenceexamples-properties-properties-qrc.html">referenceexamples/properties/properties.qrc</a></li>
</ul>
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